I have fond memories of high school, college, and early adulthood. I enjoy sharing those stories with my children & even comparing tales of adventure with other friends. The dilemma I have noticed for some people is that they are completely caught in the past. Conversation with them doesn't involve what is presently happening in their lives, but is focused only on a history of victory with no current conquests.
Why is the past so attractive to us? It's easier to talk about times in the past because no one remembers them accurately. We've taken enough liberty with the actual facts that we've accepted the story we tell as the 100% truth even if reality is somewhat less than that. We've rewritten the story so that it says what we want it to say-intentionally or not. I believe that fear is part of this reticence to move forward too because we're afraid of what we have to do now to be successful and complete. In some ways it's easier to talk about how good we used to be instead of putting in the dedicated discipline to be better today.
The past is important. It has shaped who we are today and it can be a powerful teaching tool for future decisions as long as we don't insist on dwelling in "the good old days." Faithful growth and maturity are found in simultaneously forgetting what is behind us and using it as a springboard for the future.